Marine Biologist
by DemonSword09
Summary: Percy Jackson is the Marine Biologist of the Straw Hat Pirates! A series of one-shots following interactions with crew members, fights against dangerous enemies and random shenanigans that come with being a pirate on the Grand Line.
1. Chapter 1

**Chapter 1: Sparring Practice**

The Straw Hat Pirates were adrift in the New World, the sun was shining, seagulls passed by overhead signalling that the crew was getting close to land, and there was not a marine or enemy pirate crew in sight. No, everything was perfect.

Too perfect.

"I'm boreddddd!" A certain the captain of the Straw Hat crew cried as he hung off the balcony of the Thousand Sunny by wrapping his legs around the well kept white railings. His rubbery torso and neck stretching down from the effects of gravity as he successfully covered an entire floor as he rested his raven haired head and worn straw hat on the neatly trimmed grass on the deck. A straggling finger found its way into his nose, he just wanted something... _adventurous _to happen.

Unfortunately, not all of his nakama seemed to share his desires, as Nami got to berating him. For what he will never know.

"Idiot." The orange-haired navigator chastised from her lawn chair next to Nico Robin. As sun mirror resting on her lap as glasses shadowed her eyes "The weather is relatively stable meaning nothing is going to happen to us for a while, and there's no one to fight so we won't be putting our lives in danger. This will probably be the only time ever in the New World that we will get a peaceful moment and you want to go and fight somebody."

Next to Luffy's tangled up legs, the curly haired marksman, Usopp, nodded his head in agreement, never hearing clearer logic in his life. "Yeah. Calm down Luffy, we're sure to get into epic fights with the Great and Honorable Captain Usopp at the helm. For now, just come fishing with me and Chopper."

No sooner than he said that did a smiling Luffy's face pop up in front of his own, nearly grazing the long nose. "Ok!" He cheered as the two ran to get Chopper from the medical room. Usopp gracing Luffy and the rest of the listening crew how he wrestled for forty days and forty nights with a monstrous fish just to find out it was only the tongue.

While the trio disappeared after rounding the corner the rest of the crew was on the deck taking Nami's advice to the fullest, minus Sanji who was off in the kitchen making special ice cold drinks for his lovely ladies and Franky was god knows where doing god knows what with those crazy inventions of his.

Nico Robin and Nami sat on their side of the deck in lawn chairs reading and sun bathing respectively, Percy and Zoro were relaxing on the other side. The green haired swordsman propped up against the white frame with the rolling blue ocean at his back and his three precious swords on his left. He was trying to take a nap but he was currently unsuccessful, Zoro agreed with his Captain although he didn't voice it. He needed a fight right now.

To his right a little ways off to the side sat Percy, who was turned to the swordsman, half on the railing and half off. The black haired demigod's gaze was laser focused on the sea, staring at it intently as if it held all the answers to the world. His right foot, which hung off the railing was bouncing incessantly against the grass to the beat of Brook's music. The skeleton sat in the middle playing a slow tune, acting as a mediator for the boys and the girls in a fight that would never come.

Zoro scowled behind a closed eye, right now he wanted nothing more than to train but no amount of weight lifting could improve his technique. That's when it hit him.

"Oi, Percy."

The demigod in question was snapped out of his trance, looking up from the water. Sea green eyes bored into the side of a moss green head. "Yeah?" He asked.

Zoro's one good eye, which was on side of his fellow swordsman, snapped open, onyx pupils meeting glimmering green. "Wanna spar?" He asked, getting straight to the point.

"Sure." Percy smiled, there was no need to mince words here, these two were pretty simple fellas.

The two got up, strolling to the center of the deck, letting the green grass brush against their feet. They had garnered the attention of their crewmates, off to the sides Nami and Robin had put down their book and sun mirror respectively and Brook had stop playing his music. Luffy, Usopp and Chopper had just walked out of the medical room with their arms full of fishing supplies but paused when they saw the two swordsmen at a standoff.

"Awesome!" Luffy exclaimed as he threw the supplies down and hopped up of the railing of the balcony for a better view.

"What's going on Usopp?" Chopper asked as he transformed into kung fu point so he too could get a better view.

Usopp read the situation immediately and smirked as he tipped his hat back with his index finger. "What you are about to see my dear Chopper is two of my greatest students going at it head to head in order to fight for the massive wealth I have accumulated and will pass down to my successor when I die."

"Really?!" Chopper asked excitedly. "I can believe you trained both Zoro and Percy Usopp, you're so strong!"

The chronic liar grinned "But of course, now watch carefully and maybe you might learn a thing or two from my brightest pupils."

"My, my. This should be interesting." Robin commented lightly across the deck from her seat next to Nami.

"These idiots don't even know how to relax." Nami grumbled as she pulled off her sunglasses but the archeologist wasn't fooled, the orange-haired girl had just as much interest as she did.

The scene shifted back to the center of attraction, where the battle was just beginning its developmental phase. Percy took a pen out of his jean pocket and Zoro had shrugged off the top half of the long, dark-green coat leaving his scarred skin rippling with muscle and bare to the world.

The demigod got into a crouched position, tapping the simple wristwatch on his left arm in the centerpiece. The sound of bronze metal shifting and expanding was heard and before long in the basic utensil's place was a beautiful shield engraved with Percy's past adventures from a world ago. Fighting the hydra, the minotaur, tricking Polyphemus, etc, etc. A constant on these engravings was Percy, a girl with princess curls and a boy with horns and goat feet. The crew had seen the shield in many battles before and had never asked questions. Everyone had their secrets, and everyone had their dream. Who would they be to ridicule someone else's? With the thumb finger in his right hand he flipped the pen off the cap, revealing Percy's most prized possession, Riptide, three feet of deadly bronze metal that would never harm anyone on his home planet but oddly enough could cut your average Joe here. The leaf shaped blade rested on the upper right curve of his shield, looking reminiscent to a hoplite from ancient times.

Zoro just placed his right arm on the hilt of his white sword, Wado Ichimonji.

It was Percy who broke first, charging at Zoro with blistering speed, swinging his sword in a slashing motion at Zoro's off hip. Wado came across his body in an instant, blocking the attack. The green haired swordsman crossed his left arm over, drawing Shusui from its scabbard and attacking with a fairly weak backhanded slash that clanged against Percy's shield harmlessly.

The two pushed off of each other in an attempt to create more space before the next blows were exchanged. Both swordsmen wore their signature smile, Percy had the lopsided smirk as he twirled Riptide lightly and Zoro's demonic grin stretched around the white hilt of Wado Ichimonji as he drew his final sword, Sandai Kitesu from its red scabbard. The sword sung of bloodlust as the metal scraped its way out, regardless The son of Poseidon didn't seem to put off by the cursed blade.

This time Zoro struck first striking fast and hard to keep his three swords working in tandem to put Percy off guard. The son of Poseidon had gotten as low as possible while still being viable to negate the sword Zoro swung around in his mouth like a dog would a stick, his process was simple, block one attack with his sword, the other with his shield and dodge the one in the mouth. On the strikes in quick succession the process proved to be foolproof, but when he alternating to attacking with all three swords at once and using all sorts of feints and tricks it put Percy on the defensive, not giving the demigod the time of day.

The son of Poseidon played the defensive position perfectly, backpedaling in circle around the deck as he parried the green haired swordman's blades, waiting for the time to strike back in retaliation.

Zoro struck his two swords at once, which Percy locked up with his hands, the green haired swordsman swung his neck to the side but Percy was faster using Zoro's own overwhelming power against him he pushed out against the blades to hoist himself and kick Zoro in the chest, forcing separation between the two.

Percy then did the thing no swordsman would do, he threw his sword. It sailed true to its aim and would have struck the first mate in the chest had he not sidestepped, however he took his eyes off the demigod and that was a fatal mistake.

"DOOOONG."

The sound of Zoro's jaw vibrating along with the bronze shield echoed through the air as Percy landed a vicious uppercut on the swordsman's jaw causing to drop the white blade in pain.

* * *

Meanwhile in the kitchen Sanji was making food for his two beautiful women, he strolled over to the cabinet to get some flour humming a happy tune and smoking a cigarette. The sous chef threw the doors open came face to face with the white flour, he made to grab it but was interrupted.

"SCHINK."

Percy's blade, the one that Zoro had easily sidestepped, had continued its trajectory right for the kitchen, embedding itself right where the pantry happened to be. And in a stroke of fate had not only impaled the flour but impaled it right at the exact time where Sanji had opened the doors and was directly in front of the bag, covering his face in the fine white powder.

Sanji stood there for moment in shock before moving, trying to register what happened. Finally he pieced the pieces together and realized that the bronze blade sticking through the wall was Percy's, however he wasn't going to let this spoil his mood. "Those damn bastards." He muttered as he peeled the white powder from his eyes. "It's gonna take forever to clean this up." He said as he made his way to the broom closet.

* * *

Wado Ichimonji clattered on the ground and the look on Zoro's face lead Percy to believe he had just made a very big mistake. The Thousand Sunny had fallen silent when the green haired pirate's prized katana fell to the grassy deck which tickled the two swordsmans' feet.

Reverently Zoro picked the white hilted blade up as Percy watched in silence. Onyx eyes flashed dangerously in the direction of sea green ones.

"Sorry?" Percy said weakly.

The pirate hunter grinned demonically as Wado Ichimonji was placed back in his mouth.

Not a second later the two clashed, Percy, without his sword at the moment was on the complete defensive as his ADHD and quite limited observation haki worked overtime to deflect or dodge Zoro's furious onslaught, the green haired swordsman attacked with such renewed vigor it put their previous bout to shame. The son of Poseidon could dodge most of them but with a large gash there or a small cut here could he hold out long enough for Riptide's magic to come into play?

One thing was for sure, he wasn't going to wait to find out.

With a backhanded swing Percy launched his shield on the offensive, he was by no means strong enough to land a direct hit or breakthrough Zoro's defenses for that matter but it got the desired effect as the green haired swordsman was caused to jump backwards, creating space between the two.

Immediately Percy charged, and Zoro dropped into a crouch, his swords crossed against his body in a tell tale sign that he was going to go into his signature technique 'Oni Giri'

Sure enough, the prophesied words were muttered through Zoro's white hilt as the green haired swordsman rushed to meet his opponent.

The son of Poseidon watched as Zoro closed in with speed that was reserved for the world he was currently in, as time slowed to a crawl Percy idly wondered what a child of Hermes would be like if he had speed like this. As the pirate hunter neared Percy's position he hit the deck, dropping into a roll as he collided with one of Zoro's muscled legs, sending the green haired swordsman sprawling across the deck.

But the black haired demigod wasn't finished, as he jumped up and began to wildly sprint to the bronze blade still embedded in the wall across the deck. With a mighty leap he closed the rest of the distance, and planted his bare feet against the outer wall of the Sunny, pushing off with his feet he yanked his sword out and whipped around without a second to spare as his blade met three of Zoro's own.

* * *

Sanji hummed as he was on his hands and knees sweeping up the spilt flour. His own happy tune drowned out the sounds of the black haired demigod smashing into the wall at full speed, or pushing off it with just as much force. And it most certainly missed the sound of the pickle jar tipping over onto its side, as it rolled off the shelf and onto the blonde cook's head with a mighty crash, causing a giant welt to immediately spring up.

At once, the careful visage that had been crafted by the perfect weather and thoughts of his beautiful girls in bikinis was destroyed. Now his was steaming so bad his face had grown red.

With a howl he hopped to his feet. "I AM GOING TO KILL THOSE FUCKING MORONS!" He shouted as he stormed outside.

* * *

"Baka." Zoro taunted as he stood over Percy with his three blades at the downed man's neck. "You should have realized that you were in over your head when you agreed to challenge me."

Percy bit back the retort that Zoro was the one who challenged him in the first place as a mischievous light flittered into his eyes, he felt a familiar tug in his gut.

"Ohhhhh." Luffy said, clearly amazed as he looked out into the open water. "That's a really big wave." Everyone on the deck turned to see what their captain was talking about, sure enough, a thirty foot wave was coming right at them.

Usopp, Chopper, Brook and Nami began to freak out at the massive wave, screaming about their impending doom.

Luffy clapped his sandals together and gladly told the wave to bring it on.

Robin offhandedly wondered that if this is where she would die, shooting a knowing glance at Percy.

Zoro glared at Percy too, knowing as well as Robin that he was the one behind this. "What a pathetic trick." He told the smiling swordsman as he drew back his three swords in order to disperse the wave. "1080 Calibre Phoenix!" Everyone watched as the compressed air sliced through the wave, causing the entire thing to mystify.

Zoro had no time to be proud or shoot a smug grin at his crewmates as Percy used his years of getting beat up by Clarisse on the wrestling mats in his favor, twisting the distracted swordsman to the ground and pinning him.

The son of Poseidon sat on the immobile Zoro's back. With a small chuckle he spoke. "Silly Zoro, don't you know I'm always in over my head?"

* * *

When Sanji opened the door, he expected those two idiots to be sparring, hitting each other with those over sized toothpicks, not body to body, pinning one another to the ground.

His anger gone, replaced by shock he lit a cigarette and after a long drag he blew the smoke out. "I always knew you guys were gay." He said calmly. "Congrats for coming out."

Zoro began to splutter as his face turned red while Percy smiled devilishly. "Were not, and besides…"

The occupants of the deck waited for the rest of his response with baited breath.

"He's not my type."


	2. Chapter 2

**Chapter 2: History Lessons**

Percy walked through the coral forest on the ocean floor of Fishman Island, enjoying the scenery. In the sea green eyes of the beholder, the tall coral and copious amounts of sea life blending together in perfect harmony rivalled even that of his father's palace.

He wandered aimlessly admiring the so called ship graveyard without coming in contact with one of the many sunken ships said to litter the forest yet. Currently he was on a mission to find one of these ships for two reasons.

**1**. Finding a sunken ship would be cool as fuck and he might recreate some scenes from the little mermaid with any of the sea life he might find around a wreck.

**2**. Even after a two year break where everyone had been blasted their separate ways and they didn't even know if one another was alive, Nami was still collecting interest rates. His debt was higher than his bounty at this point.

On that note, having a bounty and being a notorious villain was kind of cool. There was a small sense of giddiness the demigod felt whenever the price on his head increased. He wasn't into it on the level his Captain was, but appreciated it nonetheless.

Right now he was sitting at a clean 98,000,000 bounty. One that had remained stagnant over the last two years and was two million too short from making him a supernova.

He was brought out of his thoughts as the coral began to thin and levelled off into a clearing, one that held one of the more lesser known companions in Percy's eyes.

Nico Robin.

She sat with her back to him seemingly enraptured by the massive stone cube, but Percy had a suspicion that she knew he was there before she was. After all she could sprout eyes and ears from anywhere and was a former assassin to boot.

She was studying the pomegranate with a rarely seen intensity on the Strawhat crew, writing down what seemed to be a translation in her notebook judging by the way she went between the two.

'Wait.' Percy thought to himself as he palmed his face resulting in a loud enough slap to get the archaeologist's full attention, not that he noticed. 'Not pomegranates. Pornographs? Polygryphs? Shit! What were they called?'

As his hands continued to rub down his face, he saw that Robin had turned to stare at him. Her cerulean eyes gazing into his own with amusement shining clear.

"Hey Robin." Percy said, a light blush on his face as he began to feel guilty in front of the thirty year old, this was her dream, and he felt pretty damn inconsiderate for not even knowing what it was called, never mind what it did.

"Hello Percy-san." She said ever so eloquently as she patted the seat next to her. "Your face seems rather flushed, would you like to sit down?"

"Umm. Sure." He said as he rubbed the back of his head sheepishly, before crossing the rest of the clearing and sitting next to his fellow pirate on the stone bench in front of the por-stone cube.

For the next ten minutes or so the two sat in a companionable silence, Robin, although neither of them talked to each other or really had in the past, enjoyed the fact that someone was there with her, loneliness had plagued her her entire life, any time her crew, no her family, were there with her was a welcome change.

From the corner of her eye, she looked up at their squads Marine Biologist, he had changed little in the two years they had been apart. He was now nineteen, his hair had grown rather shaggy and untameable since then, more so than usual, as if he hadn't cut it at all. He had grown taller too, reaching a comfortable 6'2". Now taller than her unlike the opposite when they first arrived at Sabaody. There were a couple new scars that riddled his body now as well. Like the one that ran from his temple around his eye and down the jawline.

The archaeologist had overheard Usopp ask the swordsman about it and he replied gruffly that a dragon had attacked him, much to the sniper's disbelief, not that the son of Poseidon had seemed to care.

Despite all his physical changes, he seemed to not change mentally. He still squirmed when sitting still, his knees would bounce up and down, eyes darted all over the place and fingers were constantly fiddling with his pen/sword that baffled even Franky.

She figured if the choice was up to him, he'd probably be somewhere else, anywhere else so long as he was up and moving around, but he stayed behind and kept her company because Robin had offered it and he didn't want to seem rude by turning her down or getting up and leaving.

The boy, no man she could call him after seeing the way he fought at Enies Lobby, was probably the most considerate and down to earth out of all the Strawhats, only perhaps rivalled by their Captain.

"Percy-san." Robin said, his head snapped to her, those sea green hurricanes he liked to call eyes stared at her intently letting her know she had been successful at garnering his attention. "Do you mind explaining your sword to me? It seems to not follow any laws at all."

Percy smiled as he looked at the ballpoint pen form Riptide, his weapon of choice and hopefully the only weapon he'll ever need. The deadly bronze blade and more specifically its enchantments had saved his life on more than one occasion.

"That's because it's magic." He answered with a grin, uncapping the pen as it sprung into a three foot long leaf shaped blade made entirely out of celestial bronze, watching as Robin tilted her head and gave him an amused smile. The same smile she would give Usopp whenever he embarked on one of his glorious stories.

The son of Poseidon rolled his eyes, but the grin stayed on his face. "Seriously, it is. Magic fruits that give your weird powers are ok but magic swords aren't?"

Robin near condescending smile turned straight at his insistence, she adopted a more inquisitive look. "Well then what makes it magic? Do you know Percy-san?" Her nature desire for history nature getting the best of her as she accepted his logic through the use of comparing devil fruits.

Some of the light in Percy's eyes were lost at the questioning and Robin was afraid she may have overstepped his boundaries but before she could apologize he muttered a name.

"Zoe."

"Excuse me?" Robin asked politely.

The way Percy looked at her when she talked was like he had forgotten she was there at all, his eyes widened in surprise as he seemed to recall the setting they were in. "Oh sorry." He rubbed the back of his head. "Zoe's the name of my friend." He explained. "She's the one who put all the enchantments on it."

The archaeologist still looked pretty lost. With a small chuckle the black haired demigod sighed. "Guess I should start from the beginning huh?"

She nodded in the closest thing Percy had ever seen her face to get to excitement. 'Just like Annabeth. Always ready to learn' He thought somberly.

With a deep threat he banished his thoughts and tried to recollect the entirety of Anaklusmos' story. "It all started with this girl Zoe, she was something called a hesperides, who are the guardians of the dusk or something like that. I don't really remember the myth all that well. Their mother, whose name was Pleione made the sword for Zoe. Zoe's mother was a goddess who was married to a titan named Atlas, he's a bad guy but we'll get to that later."

From there on it was a tale of intrigue, magic, betrayal, a story that ended in death.

One of Heracles labors was to retrieve a golden apple from the Garden of Hesperides, and he had tricked one of the Hesperides, Zoe, to help him slay the hundred headed dragon Ladon.

In return he was supposed to whisk her away to lands unknown, all he left with was the sword.

Thousands of years later it ended up in sea god's possession, Percy's father, not that he told her so.

The sea god had passed it on to an immortal trainer of heroes who happened to be a centaur just a couple months before Percy was born. No instructions were given except 'Pass it on when the time is right.'

Then a twelve year old Percy turned around to see his latin teacher throw a sword at him. Screaming 'What! Ho!' As the boy prepared to cut down a servant of the Underworld.

For the next two years it went on multiple other whimsical adventures which Percy glossed over until the Hunters of Artemis had arrived.

Finally Percy concluded with a cross country race against the clock that ended in Zoe's death at the hands of her own father Atlas. How the titan was tricked back into its position under the sky and the huntress was immortalized in the stars as a constellation by the goddess of the moon.

"After that there were a few more battles and stuff I used in then I found Luffy and here we are." Percy finished lamely, reducing two wars, countless deaths and adventures and being transported to another world to 'a few battles and stuff.'

There was an eerie silence between the two after the story wrapped up. Robin seemed to sit there trying to process all of the information while Percy wrung his hands nervously. That was the most he's ever shared about his past life before, how someone of this world was going to take it was driving Percy mad with worry as the listener refused to open her mouth.

"That… That was quite the story Percy-san." Robin finally finished, it was hard for her to discern how much truth of that story was real, it sounded to fantastical to be true but the ship's Marine Biologist spoke with such honesty and hurt it was hard to say he was lying.

In the end she chose to believe him.

"Quite the story indeed." Percy smiled softly, agreeing with her.

"Percy-san."

"Hm?"

"When we get to the surface, do you think you could show me Zoe's constellation?"

"I'd be more than happy to."

Percy then realized he hadn't achieved his goal whatsoever in finding any sunken pirate ships or more importantly their treasure. It looked like he might be in Nami's debt forever.

But in cases like this, that was ok.


End file.
